The Chainlink Fall 2021 Hackathon kicks off October 22. Sign up today.

As a proud sponsor of ETHGlobal’s 2020 ETHOnline Hackathon, Chainlink is extending a big thank you and congratulations to all participants and hackathon winners. ETHGlobal’s virtual event was a great opportunity to see the wide variety of development at all levels of the stack from the broader Ethereum community. As a sponsor, we’re excited to support developers who are increasing smart contract usability and connectivity with Chainlink’s decentralized oracle network.

Today we’re thrilled to announce the five outstanding winners for submissions that integrated Chainlink technology. Each of the five winning projects will receive $1,000 worth of prizes.

Thank you again to all the participants, sponsors, and judges who made the ETHOnline Hackathon successful, and a special thanks to ETHGlobal for continuing to support developers and teams who are building secure decentralized technology.

Chainlink ETHOnline Hackathon Winners

The winners below are highlighted in alphabetical order.

Iroiro: Decentralized Creators Support Platform

Iroiro, an Ethereum-based creators support platform submitted by Tsukasa Noguchi and Toshiaki Takase, allows creators to distribute reward tokens to their fans’ wallet addresses using the Audius decentralized music platform. Because gas costs for sending tokens to followers can be prohibitive, Iroiro uses IPFS to save Audius supporter information as a JSON file. The supporters can then withdraw the token rewards at their convenience.

The Iroiro team created a Chainlink External Adapter to connect Iroiro to IPFS. When supporters make a withdrawal request, the smart contract uses Chainlink to check that the supporter’s address is in the JSON file to approve the withdrawal address.

The Iroiro model allows supporters to determine token properties such as token name, symbol, and total supply, as well as unique properties such as token allocation, vesting, and staking capabilities. This flexibility of options gives creators greater control over token distribution for novel, cryptoeconomic fan engagement models.

Overlay: Long/Short DeFi Data Stream Derivatives

Using an innovative approach to prediction markets, developer Michael Feldman created Overlay, a protocol that enables users to long or short the likelihood of an event using direct token adjustments as the payout mechanism. Instead of betting against other market participants, users place positions by staking synthetic Overlay tokens against data streams, predicting which direction the stream will trend (e.g., price data moving up or down). When the user exits the position, the smart contracts burn or credit the Overlay tokens to the account, depending on the data stream result.

Overlay uses Chainlink oracles to determine the likelihood of an event based on off-chain data. The live demo uses BTC/USD, ETH/USD, DAI/USD, and FastGas Chainlink Price Feeds as reference streams. Overlay also uses the ERC-1155 token standard, which allows users to sell their positions on secondary markets while retaining unique position identifiers, such as lock price, leverage factor, and whether the position is on the long or short side.

Rupia: An Indian Rupee (INR) Stablecoin Derivative

Indian Rupee (INR) stablecoin project Rupia, developed by Vijay Lakshminarayanan, is a proof of concept that allows users to convert INR fiat currency to DAI, and then stake DAI to mint Rupia stablecoins. Rupia uses a Chainlink DAI/INR Price Feed to calculate the quantity of Rupia tokens minted from the DAI.

The project has three main components:

• A fiat to DAI gateway using Transak to convert INR to Matic Network DAI. Rupia uses a React front-end to convert the Transak user interface to feature INR.
• The Chainlink DAI/INR Price Feed. The Chainlink oracle network pulls the price data from a data source (Cryptocompare in the example), then delivers the price to the Rupia ERC-20 smart contract.
• The Rupia ERC-20 smart contract uses OpenZeppelin to generate the token, and tokens are minted based on the DAI/INR Price Feed.

Rupia lays the technical groundwork for dApps to include other fiat-based stablecoin currencies that have less exposure across cryptocurrency markets.

SecretPay: Buy ETH Privately From PayPal and Revolut

Using private escrow contracts, SecretPay, built by Francesco Cremonato, allows users to make peer-to-peer ETH purchases using their PayPal or Revolut accounts. Specifically, SecretPay uses Chainlink oracles to send PayPal or Revolut invoices to Textile Mailboxes, enabling developers to integrate encrypted peer-to-peer mailboxes into Web3 apps using wallet keypairs as addresses.

Using SecretPay, a buyer sets up a purchase invoice with Paypal or Revolut, while a seller puts ETH into an escrow account. SecretPay sends the buyer’s invoice to Chainlink oracles, which read the invoice and transmit the invoice data to the buyer’s and seller’s Textile Mailboxes. The buyer and the seller confirm the invoice, then the buyer executes the purchase on PayPal or Revolut, and SecretPay sends the seller’s escrowed ETH to the buyer. This solution is a novel method for connecting widely-adopted fintech services to the rapidly growing DeFi space.

Unipeer: Fiat to Ethereum On-Ramp Using an Open Banking API

The Unipeer team, Shaleen Jain and Avie Kakkar, has created a peer-to-peer on- and off-ramping method that pulls funds from existing fiat bank accounts through encrypted open banking APIs. Unipeer calls the APIs to gain access to payment information without leaking sensitive data onto the public blockchain. Over the past several years, there has been significant growth in fintech applications using open banking APIs, which are behind many innovative fintech products enabling new applications that use traditional banking rails such as Plaid, Yodlee, and others.

Unipeer uses a custom-built Chainlink External Adapter to connect open banking APIs from a sandbox API environment to smart contracts. The External Adapter connects to a Comptroller smart contract that initiates the fiat payment process via the banking API. The External Adapter also connects to an Escrow contract to confirm fiat payment and release a seller’s escrowed funds.

Congratulations winners, and thank you to all the developers who used Chainlink in ETHGlobal’s 2020 Hackathon! We’re excited to see your participation in future hackathons as we continue to support innovative and secure smart contract development.

If you’re a developer getting ready for the next hackathon, and you need resources to get your application connected to Chainlink Price Feeds, Chainlink VRF, or access any API, visit the developer documentation and join the technical discussion in Discord. If you want to schedule a call to discuss the integration more in-depth, reach out here.

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The Chainlink Fall 2021 Hackathon kicks off October 22, 2021. Whether you’re a developer, creator, artist, blockchain expert, or completely new to the space, this hackathon is the perfect place to kickstart your smart contract development journey and learn from industry-leading mentors. Secure your spot today to compete for over $300k in prizes.